Hard magnetic compositions from iron oxide fines and methods for making same

Patent metadata

Field	Value
Publication number	US-10614939-B2
Application number	US-201515112749-A
Country	US
Kind code	B2
Filing date	Jan 29, 2015
Priority date	Jan 31, 2014
Publication date	Apr 7, 2020
Grant date	Apr 7, 2020

Abstract

Disclosed herein are compositions and methods of making a hard magnetic material from iron oxide fines, the hard magnetic material having a general formula MFexOy. In one aspect, the method comprises a) providing an iron oxide fine; b) providing a metal carbonate of a general formula Mx(CO3)y; c) mixing the iron oxide fine and the metal carbonate to form a mixture; d) calcining the mixture of the iron oxide fine and the metal carbonate; wherein M is a divalent metal ion.

First claim

What is claimed is:

1. A method for making a hard magnetic powder of a general formula MFe x O y , the method comprising:
a) providing an iron oxide fine, wherein the iron oxide fine comprises at least one member selected from the group consisting of magnetite, limonite, siderite, iron pyrite and goethite;
b) providing a metal carbonate of a general formula M x (CO 3 ) y ;
c) mixing the iron oxide fine and the metal carbonate to form a mixture;
d) calcining the mixture of the iron oxide fine and the metal for 4 to 12 hours at a temperature of at least 1000° C.;
wherein M is a divalent metal ion;
wherein the calcined mixture is re-milled in a dry atmosphere and then fired at about 1100 to 1300° C. for about 2 to 6 hours with a heating rate of 10° C. min −1 in air atmosphere to form the hard magnetic powder.

2. The method of claim 1 , wherein the iron oxide fine is a by-product of an iron processing or iron making process.

3. The method of claim 1 , wherein the iron oxide fine comprises the siderite.

4. The method of claim 1 , wherein M is strontium.

5. The method of claim 1 , wherein M x (CO 3 ) y is SrCO 3 .

6. The method of claim 1 , wherein the mixture is calcined for about 4 hours.

7. The method of claim 1 , wherein M is strontium; and Fe x O y is Fe 12 O 19 .

8. The method of claim 1 , wherein the hard magnetic powder is a ferrite.

9. The method of claim 1 , wherein the iron oxide fine comprises at least one member selected from the group consisting of magnetite, limonite, siderite, iron pyrite and goethite.

10. The method of claim 1 , wherein the hard magnetic powder is hexagonal ferrites; M is strontium; and Fe x O y is Fe 12 O 19 .

11. The method of claim 1 , wherein the iron oxide fine comprises at least one member selected from the group consisting of limonite, siderite, iron pyrite and goethite.

12. The method of claim 1 , wherein the iron oxide fine comprises at least one member selected from the group consisting of siderite, iron pyrite and goethite.

13. The method of claim 1 , wherein the iron oxide fine further comprises at least about 93 wt % Fe 2 O 3 .

14. The method of claim 1 , wherein no preheating step is required for the iron oxide fine.

15. A method for making a hard magnetic powder of a general formula MFexOy, the method comprising:
a) forming a pre-blend by mixing an iron oxide fine; and a metal carbonate of a general formula M x (CO 3 ) y ;
b) milling the preblend to form a blended powder mixture; and
c) calcining the blended powder mixture at a temperature of at least 1000° C. for about 4 hours; wherein M is a divalent metal ion; wherein the calcined mixture is re-milled in a dry atmosphere before firing the calcined mixture, and firing the calcined mixture at from 1100° C. to 1200° C. for 4 to 12 hours to produce the hard magnetic powder;
wherein the iron oxide fine comprises at least one member selected from the group consisting of magnetite, limonite, siderite, iron pyrite and goethite.

16. The method according to claim 1 , wherein the hard magnetic powder has a BH of from 1 to 3.0 MGOe at 300 K.

Assignees

• Saudi Basic Ind Corp

Inventors

• Saddik Mohamed Bahgat
• Awan Fazal-Ur-Rehman

Classifications

• C04B2235/447

  Phosphates or phosphites, e.g. orthophosphate or hypophosphite · CPC title

• C04B35/622

  Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products · CPC title

• C04B2235/3206

  Magnesium oxides or oxide-forming salts thereof · CPC title

• C04B2235/422

  Carbon · CPC title

• C01G49/0036

  containing one alkaline earth metal, magnesium or lead · CPC title